(CNN)A Pennsylvania hospital said Monday that it's telling about 1,300 open-heart surgery patients they could have been exposed to a bacterial infection after identifying eight patients who contracted nontuberculous mycobacterium, or NTM. Four of those patients died.
The Centers for Disease Control and Prevention stopped short of directly linking the deaths to the infection, as all four for of the patients had underlying medical conditions. But the hospital acknowledged that the infection probably was a contributing factor.
NTM is a naturally occurring bacterium found in soil and water, including, sometimes, tap water. People become infected by inhaling the bacteria, according to the American Lung Association. Most people do not become ill, although those with weakened immune systems are at risk. This can include someone recovering from an invasive procedure. The result is a pulmonary illness that can take more than a year of antibiotic treatment to cure.
WellSpan York Hospital in York, Pennsylvania, is contacting all patients who underwent open-heart surgery between October 1, 2011, and July 24, 2015.
"We know that the news of this potential risk of infection may be concerning to our open-heart patients, and we sincerely regret any distress that it may create for those patients and their families," said Keith Noll, senior vice president of WellSpan Health and president of WellSpan York Hospital.
In July, a study published in the medical journal Clinical Infectious Diseases found a risk of bacteria escaping from heater-cooler devices used during open-heart surgeries. The devices heat or cool the patient during surgery and usually stand about 8 to 10 feet away, said Brett Marcy, a spokesman for WellSpan Health.
According to a news release, the infection risk is thought to be limited to the patients who underwent the surgery. No physicians, clinicians, staff or patients who had noninvasive heart procedures were at risk.
"The safety, health and well-being of our patients is always our highest priority," Noll said. "That is why we took this very seriously and immediately notified state and federal health officials and requested their assistance and guidance."
The hospital also replaced its heater-cooler devices with new equipment in late July after consulting with the Centers for Disease Control and Prevention and the Pennsylvania Department of Health. "The new equipment is being meticulously maintained according to the enhanced cleaning procedures," Noll said.
He's referring to steps recommended by the Food and Drug Administration that hospitals can implement when using these devices, including not using tap water; taking environmental, air and water samples; and directing the vent of the device away from the surgical field.
They were issued as part of a safety communication from the FDA this month because the problem may be more widespread. According to the FDA, there were 32 reports of patient infections associated with heater-cooler devices or bacterial heater-cooler device contamination between January 2010 and August 2015. Of those reports, eight were in the United States, and most of the other 24 were in Western Europe, the agency said. And 25 of the reports were made this year. Not all of the reports were among patients who had undergone cardiac surgery, but some reports don't identify the procedure the patient had undergone, the safety communication states.
Last week, the CDC issued recommendations to health officials, health care providers and health care facilities to be on the lookout for any such cases and to take steps to prevent them. It is working with local and state health officials, as well as the FDA.
"The most important action to protect patients will be to remove contaminated heater-coolers from operating rooms, and ensure that those in service are correctly maintained," the CDC says.
The CDC also asks patients who have undergone cardiac procedures to tell their doctor if they were exposed to this device or if they are experiencing a combination of symptoms, including fever, pain, redness, heat or pus around their surgical incision, night sweats, joint or muscle pain, and fatigue.
WellSpan York is the second hospital in Pennsylvania associated with a potentially deadly infection in recent months. In September, the University of Pittsburgh Medical Center voluntarily suspended organ transplants after three transplant patients died after contracting a fungal infection.
Marcy stressed the situations at the two hospitals are unrelated.
"No connection between Pittsburgh and here; this is different scenario," he said.
CNN's AnneClaire Stapleton and Debra Goldschmidt contributed to this report.